Semiconducting materials find uses in many applications. For example, semiconducting materials can be used in electronic devices as processors formed on semiconductor wafers. As a further example, semiconducting materials are also used to convert solar radiation into electrical energy through the use of photovoltaics.
The semiconducting properties of a semiconducting material may depend on the crystal structure of the material. Faults within the crystal structure of a semiconducting material may diminish the material's semiconducting properties.
Semiconducting materials can be formed using a variety of different methods, at least some of which can lead to materials having less than optimal semiconducting properties. Methods by which single crystalline semiconducting materials are made include, for example, the Czochralski process. Methods by which multicrystalline semiconducting materials are made include, for example, electromagnetic casting and ribbon growth techniques. Another method for producing multicrystalline semiconducting material is disclosed in U.S. Provisional Patent Application No. 61/067,679, filed Feb. 29, 2008, titled “METHOD OF MAKING AN UNSUPPORTED ARTICLE OF A PURE OR DOPED SEMICONDUCTING ELEMENT OR ALLOY, the disclosure of which is hereby incorporated by reference.
While the Czochralski process produces semiconducting material having a single crystalline structure, the method is slow and wasteful. Wafers produced using the Czochralski process are cut from the single crystal, which leads to significant kerf loss.
Ribbon growth techniques can be used to form multicrystalline semiconducting material. The ribbon growth method, however, is a slow process, yielding about 1-2 cm/min. Semiconducting materials produced by the ribbon growth method tend to have long crystals extending in the direction of crystal growth.
Electromagnetic casting may form multicrystalline semiconducting materials in larger quantities, but the technique requires cutting the formed multicrystalline material, which leads to kerf loss. In addition, crystal grains within the semiconducting materials formed by electromagnetic casting process do not have a uniform crystal grain orientation.
In the method disclosed in U.S. Provisional Patent Application No. 61/067,679, multicrystalline semiconducting material is fashioned by forming the semiconducting material on a mold that is immersed in molten semiconducting material.
There is a long-felt need in the industry for a method to treat crystalline semiconducting materials produced by known methods, which method would improve crystal grain structure and/or surface properties of the semiconducting materials.